The Center for Prevention and Treatment Methodology (CPTM) is committed to vigorous dissemination of the methods it develops. Software development is one of our most important dissemination vehicles. The Software Development and Technology Transfer Core (Software Core) is a resource forthe entire CPTM. Staff ofthe Software Core will assist CTPM scientists as they seek to implement, test, apply, document, and disseminate their methods for maximal benefit to substance use and HIV prevention and treatment scientists. In addition, the Software Core assists CPTM scientists in other aspects of research related to computer usage, efficiency in simulation studies, handling of data, and dissemination. The Specific Aims of this Core are: 1. To collaborate with the four CPTM scientific projects to create, document, and maintain user-friendly and reliable software that implements methodologies developed under those projects; 2. To implement the CPTM data and safety monitoring plan for use of empirical data on behaviors related to substance use and HIV; 3. To develop and maintain the CPTM public website; 4. To leverage new multimedia platforms for increased dissemination of scientific content and networking among scientists focused on behaviors related to substance use and HIV; 5. To manage the CPTM computing systems and provide computer-related technical support; and 6. To help CPTM researchers run simulations and other computationally intensive applications on a university high performance computer cluster. The Software Core in the current CPTM maintains a web site packed with methodological information. Over 1700 users have registered to download our software. This software includes PROC LCA, PROC LTA, and PROC SCADLS; SAS macros for the analysis of intensive longitudinal data; and web applets. Plans for the future include new releases of current software; software for new applications, such as causal mediation; and branching out into Stata plug-ins. The Software Core is an important shared CPTM resource and a highly effective means of placing the innovative methods we develop in the hands of prevention and treatment scientists.